With the continued concern over global climate change there is an increasing need to develop technologies to replace those with high ozone depletion potential (ODP) and high global warming potential (GWP). Though hydrofluorocarbons (HFC), being non-ozone depleting compounds, have been identified as alternative blowing agents to chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) in the production of thermoplastic foams, they still tend to have significant GWP.
It was discovered that blowing agent compositions comprising a hydrochlorofluorolefin, particularly HCFO-123zd, HCFO-1233xf, dichloro-fluorinated propenes, and mixtures thereof can permit the production of lower density, closed-cell foam and good k-factor which will be particularly useful for thermal insulating foams. This invention may also permit the production of low density, closed-cell foams with enlarged, controlled cell size.
WO 2004/037913, WO 2007/002703, and US Pat. Publication 2004119047 discloses blowing agents comprising halogenated alkenes of generic formula that would include numerous HCFOs, among many other materials including brominated and iodinated compounds and HFOs. Specific HCFOs for use in thermoplastic foaming are not disclosed nor are the benefits of using the HCFOs in terms of increasing the foam cell size as discovered in the present invention. HCFO-123zd is disclosed for use in polyurethane foaming, however it is not obvious to one skilled in the art that a blowing agent for polyurethane foaming would be particularly good for thermoplastic foaming.
GB 950,876 discloses a process for the production of polyurethane foams. It discloses that any suitable halogenated saturated or unsaturated hydrocarbon having a boiling point below 150° C., preferably below 50° C., can be used as the blowing agent. Trichlorofluoroethene, chlorotrifluoroethene, and 1,1-dichloro-2,2-difluoroethene are disclosed in a list of suitable blowing agents. Hydrochlorofluoropropenes are not specifically disclosed nor are longer chain HCFOs. There is no disclosure related to blowing agents for thermoplastic foaming nor are the benefits of HCFOs in thermoplastic foaming mentioned nor preferred combinations of HCFOs with other coblowing agents.
CA 2016328 discloses a process for preparing closed-cell, polyisocyanate foam. Disclosed are organic compound blowing agents including halogenated alkanes and alkenes, where the alkene is propylene, and the halogenated hydrocarbons can be chlorofluorocarbons. Among the many exemplary compounds listed are specific chlorofluoroethylenes containing 1 chlorine and from 1 to 3 fluorines. Hydrochlorofluoropropenes are not specifically disclosed nor are longer chain HCFOs. There is no disclosure related to blowing agents for thermoplastic foaming nor are the benefits of HCFOs in thermoplastic foaming mentioned nor preferred combinations of HCFOs with other coblowing agents.